Photoluminescence lifetime in silica glasses excited by vacuum ultra violet laser irradiation

Photoluminescence bands in silica glasses excited by a VUV (vacuum ultraviolet) laser (7.9 eV) are reported. Luminescence spectra of various types of silicas, prepared under different conditions, exhibit sample-to-sample variations. Several luminescence bands (1.9-eV, 2.7-eV, 3.1-eV, 4.2-eV, 4.3-eV, and 2-4-eV bands) were observed at room temperature. The 2.7-eV band, previously ascribed to a triplet-to-singlet transition of neutral oxygen vacancy, shows a slow decay rate of tau approximately=10 ms. Relatively slow decay rates of tau approximately=15 mu s and tau approximately=110 mu s were obtained for the 1.9- and 3.1-eV bands, respectively.<>